This casebook remains the most comprehensive available on water law. It gives extensive coverage to both Eastern and Western common law, customary and statutory allocation systems, Indian water rights, and interstate allocation law and the historical forces that produced these systems. It also covers the federal government’s historic role in constructing irrigation, flood control and navigation projects and the changing roles of local water supply organizations. All chapters emphasize the challenges that states and the federal water resources agencies are facing such as climate change adaptation, environmental restoration and the reallocation of existing entitlements.